Sage Sri, Sankara himself had often said that his philosophy was based on Sruti or revealed scripture. This may be because Sage Sri, Sankara addressed the ordinary man, who finds security in the idea of causality and thus, in the idea of God—and Revelation is indispensable to prove the latter. He believed that those of superior intelligence, have no need of this idea of divine causality, and can, therefore, dispense with Sruti and arrive at the truth of Non-Dualism by pure reason.
Only through Soulcentric reasoning, one will be able to cross the domain of the form, time, and space.
Ashtavakra Gita: ~ It is not the absence of Buddhi (reason) that can grasp Advaita but the man who possesses the highest intellect. Brains are necessary. Such a man, by merely hearing the truth mentioned will know it. (Page~ 224).
The one who possesses the highest intellect can grasp Advaitic truth, by merely hearing the truth mentioned will know it.
Bhagavad Gita: ~ Reason as means to reality. (Chap.18 verse 37)
In chap. 10 of in Bhagavad Gita, Krishna says: ~ I cannot save you, but I can give you Buddhi (reason). (chap. 10)
In chap. 10 of in Bhagavad Gita, Krishna says: ~ "I have given you the most secret teaching, now reflect over it all" Krishna plainly says reflect, think. (Verse 63 of Chap. 18)
Mundaka Upanishad says: ~ Both states are harmful and take you away from the path of inquiry into truth. (Page 234)
Reasoning is interpretable in two ways. The egocentric interpretation is to apply it only to the practical purpose (waking experience). The Soulcentric interpretation is to apply it to the three states. The latter leads to the final settlement of the problems because it takes all data into consideration.
The Soul is the innermost Self. The Soul is present in the form of the consciousness. The Consciousness is the ultimate truth or Brahman. The Ultimate truth or Brahman is God. Realize the consciousness as the ultimate truth or Brahman. The consciousness is existence, knowledge and Absolute awareness. The consciousness is non-dual and infinite, eternal and ‘one’ and which fills all that exists.
Self-realization is the realization of the Advaitic truth. There is nothing more to be realized other than the truth, which is beyond the form, time, and space.
After acquiring the Self-knowledge or Brahma Gnana Knowledge or Atma Gnana nothing needs to be acquired. Self-knowledge or Brahma Gnana Knowledge or Atma Gnana frees the Soul, the innermost self from the dualistic illusion. When the Soul is free from the dualistic illusion then it is free from experiencing the illusory birth, life, death and the world as a reality.